Electric clock



May 12, 1925.

1,537,395 H. E. WARREN ELECTRI C CLOCK Filed Nov 14, 1922 Inventor:

H I s Attorn ey,

Patented May 12, 1925.

UNITED STATES PATENT OFFICE.

HENRY E. WARREN, OF ASHLAND, MASSACHUSETTS, ASSIGNOR TO WARREN CLOCK COMPANY, A. CORPORATION OF MAINE.

ELECTRIC CLOCK.

To all whom it may concern:

Be it known that I, HENRY E. \VAuaE-N, a citizen of the United States, residing at Ashland, county of Middlesex, State of Massachusetts, have invented certain new and useful Improvements in Electric Clocks, of which the following. is a specification.

My invention relates to electric motors for driving clocks or other apparatus which is to be driven at a predetermined substantially constant speed, and its object is to provide an inexpensive mechanism of the class specified which is accurate in operation and which requires a minimum of electric energy for its operation. A further object of my invention is to provide such a mechanism which will erform the function of amaster clock on e ectric systems for the dis-' tribution of time by means of secondary clocks.

The features of my invention, which I believe to be novel and patentable, will be pointed out in the claims appended hereto. The preferred construction and operat on of a motor built in accordance with my invention will now be described in connection with the accompanying drawing, which 11- lustrates my invention applied to drive the hands of a clock and to control a secondary clock system.

Referring to the drawing, 1 ind cates the hands of a clock driven by my mproved mechanism through a suitable tram of reduction gears 2 and a ratchet wheel 3. The ratchet wheel is operated by 'a pawl 4 which is pivoted at 5 to the upper end of a-pendulmn 6. This pendulum is pivoted at 7 and it will be seen, that if the pendulum 18 caused to oscillate in the usual manner, pawl 4 will 'catch into a tooth of wheel 3 as the lower end of the pendulitm swings to the left, and rotate said wheel in a clock-wise direction. As the pendulum swings back tolhe right, pawl 4 will be carried to the left and will ride over a tooth in wheel 3. A backward rotation of wheel 3 may be prevented. by a pawl 8, if necessary. Ordinarily the pawl 8 may be omitted. as the pawl 4; is very light in weiglrt and the natural friction of the gearing between wheel 3 and hands 1 will generally be sufiicient to prevent any backward rotation thereof when paw] 4 is moved to the left. As thus far (Ii-scribed the mechanism constitutes a form of clockwork from which the usual main spring and escapement have been omitted.

The means provided for keeping the pendulum in operation constitutes What may be appropriately termed an electro-gravity pendulum drive, since it utilizes both of these forces for its operation. This motor consists of an electromagne-t 9, an armature 10 therefor, a pivoted weight 11, a lever 12 secured to and operated by the armature 10, which serves as a movable support for weight 11, an adjustable stop 13 for lever 12, an adjustable stop 14 for weight 11, and a contacting device 16 moved by the pendulum for controlling the circuit of electromagnet 9 and utilizing a suitable source of electric energy 15. The weight 11, which is freely pivoted at 17, is held in the raise position illustrated by means of lever 12 when electromagnet 9 is de-energized. When electro-magnet 9 is energized, armature 10 is raised and lever 12 is rotated about its pivot 18 sothat said lever no longer serves as a support for weight 11. The weight 11 therefore rotates about its pivot 17 due to the action of gravity, until an arm 19 thereon comes against stop 14 and arrests its movement. The free end of weight 11 is positioned so as to be slightly raised from the upper position illustrated when contact arm 16 on pendulum 6 comes in contact with the under edge of the weight at the end of the normal swing to the right. The contact arm 1 16 is preferably made of spring material, such as steel wire, and may be adjustably sccured to the pendulum stem by a few turns 20. The contacting of arm 16 with the lower edge of weight '11 is therefore without shock or chattering; When arm 16 contacts with weight 11 the circuit of electromagnet 9 is closed from source 15 through line 21, the stem of the pendulum 6, arm 16, weight 11, line 22, the coil of the electromagnet and back to the other side of source 15 through line 23. The energizing of electromagnct 9 'causes its armature to. be raised and the support for weight 11, formed by lever 12. to be lowered out of reach of weight 11 in its lowest position, which position is determined by stop 14. Pendulum 6, together with arm 16, have by this time reached the extreme end of their swing to the right and have. just started to return. The action of gravity acting on weight 11 gives the pendulum 6 just the correctimpulse to operate the clock movement through pawl 4 and keep the pendulum in normal oscillation. This is possible because the weight 11 is always raised the greater part of its up-. ward movement by lever 12, which performs this function as soon as the contact between 16 and 11 is broken, while during itsentirc downward movement it is acting upon pendulum 6 through arm 16.

The upper and lower positions of weight 11 are adjustable by means of the adjustable stops 13 and-14 respectively, and the normal swing of pendulum 6 may be varied in the usual way by adjusting the length of the pendulum stem or the position of the pendulum bob. The clock may therefore be accurately timed, and the impulses adjusted to the correct strength to keep the clock in operation without lost motion. It will be seen that the impulses are imparted to the pendulum at the same time the awl 4 starts to move the clock gearing. onsequently the greater partof an impulse is directly imparted to and is utilized in accelerating the clock movement. The swing' of the pendulum is therefore substantially normal.

Furthermore, it will be evident that the clock movement, although intermittent, is,

nevertheless, free from sudden jerks, because.

itstarts and stops gradually with the beginning and end of a pendulum swing. The

number of teeth on ratchet wheel 3 will ofcourse be made such that the wheel is advanced the same distance each time. .Preferably the movement of pawl 4 will be made such as to slightly overreach the distance of one tooth, so thatjthe clock will always be advanced the same distance each time, irrespective of slight variations in the length of the pendulum swing. The operation of the motor mechanism may be made substantially noiseless by providing buffers 24 made of rubber or other suitable material at the abutting surfacesof the moving parts. Thelever arm 12 which carries the armature 10 will preferably be made of non-magnetic material, such as brass. i y

The movement of armature 10 and lever 12 ma very conveniently be utilized to con trol t e energizing circuit of a time dietributing system 25, to which secondary clocks 26 areconnected. These secondary clocks may be driven through a pawl and ratchet device operated by an electromagnet connected across the system 25, as indicatedin 29, or said secondar clocks may be actuated in any other suita 1e manner. In order to intermittently. energize system 25, I pro vide an adjustable stationary contact 27 connected to one side of source 15 and positioned to cooperate with a movable contact 28 carried on the free end of lever 12. These contacts serve to make and break the energizing circuit of system 25,- the other side of which is connected to the other side of source 15. The operation of the complete system may be described as follows: The master clock will first be adjusted to keep accurate time, the various stops 13, 14, and 27 adjusted to prevent lost motion and the master clock and secondary clock hands turned to register, let us say, twelve oclock. Then at exactly twelve oclock the master clock will be started in the same manner as an ordinary pendulum clockis started; that is to say, by giving pendulum 6 an initial swing sufiicient to bring contact arm 16 into contact with weight 11. This causes electromagnet 9 to be energized and lever 12 is therefore turned about its pivot 18 to remove the support for weight 11 and to close the circuit of the secondary system' 25 clocks 26 are advanced by the electric pulse sent over. the system 25 the same amount that the master clock is advanced due to the swing of pendulum 6 to the left, which now takes place, the weight 11 giving said pendulum the correct impulse to move the clockwork and keep the pendulum in operation. As soon as arm 16 moves away from weight 11 the circuit of electromagnet 9 is broken and lever 12 again takes the position illustrated in the drawing, de-energizing system 25'and raising weight 11 to the position shown. Pendulum 6 swings to the left and returns to again bring arm 16 into contact with weight 11, and the action just described is repeated. The master clock and secondary system will continue in operation as long as the source 15 is available, or until the pendulum 6 is brought to rest by hand.

It will be evident that the time of the pendulum swing may be adjusted to some extent by varying the ratio of g, where (5 represents the distance weight 11 is raised by lever 16Qat the end of a swing to the right, and 03 represents the distance said weight falls in imparting an impulse to pendulum 6. Thus by increasing the ratio The apparatus described is simple and rugged in construction; requires little, if any, lubricant; is not afl'ected by ordinary temperature changes; may be operated by either direct or alternating current with a ,through contacts 27 and 28. The secondary small consumption of energy, and will per form satisfactorily and accurately for long periods of time without attention. While I have described my improved motor pendulum drive operating a clock, Ido not 7 wish to be limited to this particular use, as it will be evident that the motor is adapted to drive other apparatus, requiring a small torque where a substantially constant speed is desired. The various parts may be rearranged and reproportione'd and the electrical contacts changed to suit different conditions Without department from the true spirit .and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States,

1. A constant speed motor comprising an electromagnet, a movablearmature lever therefor, a pendulum provided With 'a contact for controlling the ener izing circuit of said electromagnet, a weig t pivoted in such a manner as to be raised by the movement of said armature lever and to impart an energy impulse to said pendulum in falling and a rotary timing device driven by said pendulum.

2. 'A constant speed motor comprising an electromagnet, a pivoted armature lever therefor having energized and deenergized positions, a pendulum having means for controlling the energizing circuit of said electromagnet and a pivoted weight positioned to be raised by the movement of said armature lever to its deenergized position and to impart an impulse .to said pendulum at an extremity .of its swing when lowered from said raised position due to the energizing of said electromagnet.

3. A constant speed motor comprising the combination of claim 2, characterized by the fact that the pendulum carries a contact which closes the energizing circuit of the electromagnet by coming in contact with said weight near the end of. the pendulums swing.

4. A constant adjustable speed motor comprising an electromagnet, amovable armature lcver therefor, a pendulum provided with a contact for controlling the energizing circuit of said electromagnet, a weight pivoted in such a manner as to be raised by the movement. of said armature lever and to impart impulses to said pendulum in falling and means for adjusting the distance said weight shall fall independently of the extent of movement of said armature lever.

5. An electric clock comprising in com-' bination a clock hand, a pendulum operated ratchet wheel for driving 'said hand and means for imparting impulses to the pendulum at an end of its swing of sufiicient strength to keep the pendulum in operation and drive said clock, characterized by the fact that said impulsesi are imparted to said pendulum during the same hands, a pivoted Weight for directly imparting gravity impulses to said pendulum at an extremity 0 its swing, an electromagnet controlled by said pendulum and means actuated by said electromagnet for raising said weight. 1 r

7. A clock system comprising a clock movement driven by a pendulum operated ratchet wheel, a pivoted Weight for imparting. impulses tothe pendulum at an extremity of its swing, an electromagnet provided with a movable armaturelever for raising said weight after each impulse, the energizing of said electromagnet being controlled by the pendulum, and a secondary clock system controlled by the movement of said armature.

8. In a clock system, comprising a master clock, a 'sec ondary clock and a source of electric energy for operating said clocks, a motor mechanism for operating said master clock and controlling said secondary clockcomprising a ratchet wheel geared to the hands of the master clock, a pendulum for operating said ratchet wheel, a pivoted weight arranged to fall and impart impulses 'to said pendulum at an extremity of its swing, an electromagnet provided with an armature lever for raising said weight after each impulse, contacts in the energizing circuit of said electromagnet controlled by said pendulum and contacts in the energizing circuit of said secondary clock controlled by said armature lever.

9. A constant speed motor'comprising a pivoted weight, an electromagnet, an armature-lever therefor having energized and deenergize'd positions, said armature lever serving as a support for said weight in the deenergized position, a pendulum provided with a contact arm associated with said weight in such a manner as to slightly raise said weight from said support at an extremity of the swing of the pendulum,

an energizing circuit for said electromagnet adapted to be energized when said arm contacts with said weight whereby said support is removed and' an impulse imparted to said pendulum due to the subsequent falling of said weight, and an adjustable stop for said weight for determining the extent to which it shall fall.

In Witness whereof I have hereunto set my hand this 9th day of November, 1922.

HENRY E. WARREN. 

